Let's play the "was that really a book?" game

Last night I had a dream which I'm like 80% sure was based on a book I read as a kid/teen and it's bugging me:

The setting was a mish-mash fascist dystopia YA. When you reached 14 there was the typical Coming Of Age Training and Choice, you drank a liquid because of Reasons, and it turns out it has a certain probability of killing you. In the dream the good outcome was that if you'd been chosen for Strategy it counteracted the intelligence dampening drugs they put in the water supply (which I'd been secretly avoiding somehow anyway. So it was nice to stop having to pretend to be as unintelligent as everyone else. YES DREAM NICE SYMBOLISM) But it's the liquid that can kill you that's bugging me.

And now random dream ramblings:The liquid tasted like the minty mouthwash I used every time I got my plate calibrated at the dentist when I was around 14, and the guy who died had the same name as a guy I knew in primary school with the same birthday as me who died suddenly of heart failure when we were in highschool. And then at some point I was no longer our Plucky Teen Heroine and was me, 34 year old woman who knows the plot but has zero training or fitness, and the plucky revolutionary teens had to help me Not Get Everyone Killed. Just as I was screwing up a training exercise I woke up. Meanwhile the setting was like this unholy mashup of Attack on Titan, Divergent, The Hunger Games, Homestuck alpha timelime (there were actual evil clowns) and His Dark Materials, plus all the half remembered facist dystopia YA I read as a an actual young adult before realising I actively dislike the genre (I know most of those titles through cultural osmosis).

I have a strong memory of drink that was poison but the right people survived not sure which book it was in - I'd have to go and look it up, but don't have my copies easily to hand, nor enough time to read them all.